The present invention relates to a cathode ray tube device (hereinafter abbreviated as CRT) for picture display in a television set or the like.
Two desirable qualities for CRTs are high mechanical strength and lightweight. For this purpose, CRTs with funnels made of metal instead of glass are disclosed, for example, in Japanese Patent Kokai Publication 86033/1990. In these CRTS, a high voltage of 25 KV is applied to a thin metal film that covers the phosphor screen of the faceplate, while the metal funnel is grounded. Unfortunately, factors such as dirt on the inside surface of the faceplate and ambient electrons have caused serious problems of creeping discharge between the metal film and the metal funnel.